Archive for April, 2014

Fair and warmer the next two days then the last Storm of April to roll in Friday AM…..Although it will be a cold opener….Warmer weather is on the way beginning Sunday then well into Tuesday…….

 

Wednesday PM Update:

there are a lot of opinions several of the Dweebs out there, including forecasters’ from the east coast to the west on what this storm is going to do.  The QPF from HPC is deafening with amounts suggestive of 2.4 inches which is pretty amazing but not unusual for the Fishing Opener Weekend.

I just spoke with the lead forecaster at WSFO RNO this afternoon and he was definitely a dry foot compared to HPC, giving the Sierra about a foot over the crest for the Friday-Saturday period. The emphasis is on late Friday afternoon and evening.

 

Here is a copy of HPC discussion of a wet foot perspective….

THE START OF A RATHER UNSETTLED FEW DAYS ACROSS THE WEST… AS PAC DYNAMICS WHICH WILL ARRIVE INTO THE PAC NW ON THURS IS FOLLOWED BY A RATHER POTENT DIGGING UPPER JET TO HELP ESTABLISH A RATHER AMPLIFIED UPPER TROUGH AXIS ALONG THE ENTIRE WEST COAST ON FRI WITH THE SRN STREAM TAKING OVER ON SAT AS A DYNAMIC UPPER TROUGH WITH SLIGHT NEG TILT ROLLS INTO THE DESERT SW. ON FRI… LOWERING UPPER HEIGHTS WILL CRASH DOWN THE WEST COAST AND GRADUALLY TAP INTO A PLUME OF ANOMALOUS PAC MOISTURE CONTENT… 850-700MB MOISTURE FLUX ANOMALIES 2 TO 3 TIMES ABOVE AVG… FOR WIDESPREAD QPF. THE MAIN FOCUS OCCURRING ACROSS NRN/CENTRAL CA AND SIERRA INTO A LARGE PORTION OF THE INTER-MOUNTAIN WEST FROM NV TO ID. THEN ON SAT… THE IMPRESSIVE UPPER JET DRIVES THE SHORT WAVE TROUGH AND DEVELOPING CLOSED MID-LEVEL LOW THROUGH SRN CA AND INTO THE WRN EDGE OF THE FOUR CORNERS REGION. ITS THIS DAY… WHERE A LONG FETCH OF HEALTHY PAC MOISTURE INTERACTS WITH SUBTROPICAL JET DYNAMICS FOR WIDESPREAD QPF ACROSS MUCH OF THE WRN STATES. ECMWF 850-700MB MOISTURE FLUX ANOMALIES BECOME OFF THE CHARTS GENERALLY RANGING FROM 4 TO 5 TIMES ABOVE AVG. THUS EXPECT QPF FROM CENTRAL/SRN CA AND AZ NORTHWARD THROUGH THE INTER-MOUNTAIN WEST INTO THE NRN ROCKIES/PLAINS. WPC GENERALLY FOLLOWED A BLEND/COMPROMISE OF THE ECMWF/UKMET WITH THE INTERNAL PSEUDO BIAS CORRECTED GUIDANCE BOTH DAYS WITH ASSISTANCE FROM PRISM DATA TO HIGHLIGHT THE FAVORED WRN TERRAIN.

 

Updating………

 

Wednesday AM

Brief Update:

Models continue to flip-flop with now the EC showing more of a split on last nights 00Z run while the 06z GFS was better in a more progressive solution. New 12z GFS out through 96 hours is very encouraging with QPF amounts in the 1.00 to 1.5 range for the Sierra South of Tahoe. If the ECMWF in its 12z Wednesday run is in line with the GFS then will be in a higher confidence situation.

The Dweebs understand that we are right in the mists of transition season and the models do not handle storms of this nature very well.  However, this will be a cold storm with -8C at 700MB down here Saturday AM and the fishing opener is going to be cold with possible mid to upper teens for the opener over Long Valley at day break….so dress warmly. High temps will climb into the low 50s during the day Saturday,  and Sunday will be warmer, then substantially warmer Monday and Tuesday.

The Dweebs are still sticking with a good 12 inches to as high as 18 inches over the upper elevations by Saturday AM…..  This is a difficult storm to forecast QPF wise because of how late it is coming in……

Will Update the QPF time permitting this afternoon….

Longer Range:

The MJO is forecasted to move into phases spaces 8-1 during the week two period. This is usually highlighted by a Cold East and a warm west.  If you look at the analog’s for the past couple of discussions you will see why.

It is what happens after phases 8-1, which gets us into weeks late 2 and 3 where the Air Sea Coupled CFS may be hinting at. I have seen plenty of Mays living here in Mammoth for over 35 years with generous snowfalls for the upper elevation while the town gets little. For you die hard skiers and borders, after this weekend there may still be another one or two snow producing systems in May!

 

The Dweeber……………………………….:-)

Expect 5 feet of Wind and a few inches of Snow from the Tuesday system then fair and warmer Wednesday into Thursday before the next system moves in Early Friday into Saturday…..Longer Range Discussed….

 

Tuesday AM UPDATE:

FROPA occurred about 8:00am this morning and the period of moderate snow has ended as well.  It was nice to see some snow falling as it has been a while since that has happened.  Mammothweather.com picked up close to an inch of snow while the roads being warm from the past couple of days of low 60s showed wet streets in town. Mammoth Mt probably picked up 1 to 3 inches top bottom.  Outside of some scattered snow showers little in the way of accumulation is expected the rest of the day…..possibly another inch or so… The WX front is moving through the Owens Valley at the moment with strengthening winds…A high wind warning is in effect for the Owens valley today.

It will be some 10 degree warmer Wednesday and another 3 to 4 degree of warming is expected Thursday.  Highs in the upper 50s for Thursday.

The next significant weather system will move into the area about Midnight Thursday. The GFS is back to the idea of digging the Vort center further south as the system splits.  It is interesting to note that there is still a small pocket of -30C at 500MB up over extreme Northern CA Friday AM. However, at 700mb, as the -10C approaches the central coast by 18Z, as the split occurs, it gets left up over Northern California. Thus the energy headed for the Central Sierra weakens rapidly Friday Afternoon.

So the latest 12Z GFS model run continues to waffle while the EC still has more of a consolidated system coming through for Friday.  At this point, given the time of year, the GFS may have the better solution. However, in looking down stream, I do not see any real blocking to cause this split.  Everything seems pretty progressive across the country, although ridging is starting to build over the nations midsection. So the upshot here is if the GFS is correct, QPFs of at least half of what has been touted the past few days will occur resulting in snowfall amount’s of less than a foot.   I will wait for another run or two of the EC to see if it too has the same idea. Will report later today, time permitting.

PS;

I forgot to mention that there is some over running coming in Saturday late AM into the afternoon lasting into the evening. This is from a strong northern pacific upper jet of a good 150 knots. It is riding atop of a building eastern pacific ridge that will eventually build over California early next week.

By late Tuesday, temps at 700MB will approach +7.5C over  Mammoth and up to +10C over Southern California. This is quite the Anti-Cyclone and quite warm. Back to the over running…There is not much QPF from that system. Over running is just mid level moisture over running the cooler air in place. So there may be a period of light snow or showers during in the day Saturday into the evening. Thereafter, we ridge up early next week with vengeance and remain fair for sometime.  As I mentioned in the past discussion, we may have another active pattern develop the 2nd week of May according to the Air-Sea coupled CFS.  I will report on that later in the week.

Dr Howard and the Dweebs………………………………;-)

 

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Local forecasts will reflect an increase of wind this afternoon along with lots of high cloudiness….

The weather system coming in Tonight will favor the Pacific Northwest as the main forcing and upper “jets” couple up over the pacific Northwest today. The Rt rear entry region passes over  Mammoth Tuesday AM and thus that will be the best time for showers locally. The snow level will begin high. About 8500 tonight then fall to about 6500 by AM. The best time for showers will be about 15Z Tuesday. (8:00am) as a small area of 50% RH at 700MB moves through with the approaching vort center and WX front. The last Vt max will be east of Mammoth by 21Z Tuesday. Amounts??? 1 to 3 inches.  Best Guess…

Upper ridging will follow, however, it is short wave ridging. This leaves the door open for an even stronger system Friday.  The new 12zGFS has the cold pool at -2.5 SDN)   What I did not like about the 06Z run last night was the system splitting with a closed upper center developing off the SC coast Friday night.  This would reduce the QPF substantially. However the 00z ECMWF and the new 12Z GFS runs has the system holding together better. The New 12Z gfs has the upper low closing off over interior CA after the main dynamics has moved through the Mammoth area Friday.  Friday is ShowTime….Saturday is just cold and showery with the possibility of some mid morning upslope.

So the way things look today….The upper jet still hooks into and through Paso Robles which is not only known for great vineyards but also one of the best upper jet entry regions for the Mammoth Area!    😉

This will be a plow for the snow pushes in town Friday Evening with clean up Saturday AM…

It is looking like 12 to 18 inches over the upper elevations at this time.

Expect warming temperatures Sunday into the following Monday.

Longer Range:

Once again I had a look at the CFS (Climate Forecast System) for the long range.   Here are my thoughts….  Normally, in many La Nina years, winter ends quickly. Summers are often warmer then normal over the interior of the Great Basin away from the coast as its colder waters effects the marine layer.  However, we are no longer in a La Nina, but trending quickly toward El NINO.  The MJO that has been stuck in phases 6 through 7 much of the winter was not conducive or at the least did not add much support to precipitation here in Central and Southern CA . That became dislodged in March, possibly because of the great Kelvin Wave now sloshing up against the Central American coast. Over the past 45 days the MJO cycled nicely through phase’s 1. 2. 3, 4 , 5 and now 6. If that were to have happened in January and February we would have had quite a few good storm’s, based upon the MJO teleconnections.

So what has happened?

Argument for a wet May….A strong Kelvin Wave that began over the western pacific has slowly traveled across the pacific to the Eastern Pacific. The warm sub and surface waters have flipped the ENSO sign throughout most of the ENSO regions.  If you recall during strong EL Nino Winters, they no not die quickly, they tend to fade away…..sometimes lasting into early July! Like during the winter of 82-83.  Could the CFS which is a *Ocean/Atmospheric *coupled model be telling us that a cool Spring is in the making?  The latest CFS Run has the precipitation over Northern and Central Sierra up to 130% of normal as well as 3 standard deviations of normal for the month.  Of course, one could argue that we do not get much precip during the month of May anyway…..but this is significant.

Argument against a wet “Early May”:

Using the Dynamic MJO Model based upon the GFS Ensembles….the Location of the MJO in phase spaces 8-1 for the month of May suggests higher then normal heights over CA.

 

SEE: for phase 8           http://www.americanwx.com/raleighwx/MJO/MJO/MayPhase8500mb.gif

SEE: For Phase 1          http://www.americanwx.com/raleighwx/MJO/MJO/MayPhase1500mb.gif

So the question may be, what happens later in the month of May?

Dr Howard and the Dweebs………………………………….;-)

 

*The “Coupled” in the model’s name refers to the fact that the model couples both atmospheric modeling and oceanic modeling into one all-purpose model. Its forecasts are derived from a 16-member ensemble with each member initialized on a lead of several days worth of conditions. The CFSv2 offers output that can be masked to remove forecasts with insufficient skill.

 

A Splitting Trof along with small upper closed low will kick off a few showers later this afternoon and evening……The weekend weather will bring a mixed bag of Sun…Clouds and Some Isolated showers Saturday then warmer Temps by Sunday into Monday…..A more active pattern develops later next week……

Sunday PM:

 

It looks like the winds will be picking up Monday as the first in a series of short wave trofs begin their migration into California. The first system for Tuesday will really cool things down with highs Tuesday in the 40s, followings by nighttime lows in the 20s. The upper jet is mostly to our north with the RT rear entry brushing Mono County. Moisture appears to be sparse as well as the Dweebs are only expecting mainly snow showers and the possibility of up to 2 to 4 inches over the crest and an inch or so at 8000 ft by Tuesday afternoon.

Short wave ridging will follow Wednesday into Thursday with breezy weather especially over the upper elevations Wednesday and light breezes Thursday. Temperatures will climb into the 50s on Wednesday, then peak out to near 60 by Thursday.

As mentioned in my last posting, the following storm for next weekend is a different animal. A cold pool at 500mb of -27C and 700mb temps of -10C Saturday AM is over Mammoth Saturday AM. This is suggestive of a major system for the Central and Southern Sierra.  The system will split a bit while coming in, as it becomes negative tilt. However, with the cold pool digging so far south, the most dynamic part of the storm will be more over Central CA as the models show a cyclonically hooked upper jet with Central CA in its front left exit region.

Based upon the 12z ECMWF guidance, this storm has a QPF of about an inch over the upper elevations. That is about a foot at between 10-12:1 over the crest.  The GFS has between 1.5 and 1.8 inches of QPF and the bulls eye keeps moving around with various runs. The Dweebs will take another look at it in the morning….then track it the rest of the week….

The bottom line is the although this system is not nearly as cold as the storm that the Dweebs called a Platinum Powder alert on, it will still be good quality powder over the upper elevations!

 

Dr Howard and the Dweebs……………………..:-)

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As we approach the end of the 1st 30 days of Spring, the weather has for the most part been above normal temperature wise, and below normal precipitation wise here in Mammoth. The Dweebs see a reversal of that pattern over the next 14 days. To begin with, more blocking is forecasted over NW Canada and this blocking is expected to build North Westward into Alaska, well into week two.  The end result would be a more active pattern over the west with cooler than normal temperatures developing by midweek next week, and normal precipitation for the week 1 period then “above normal” precipitation for week 2 for Mammoth Lakes (IE the 25th through the 30th). The next weather system that will approach our area early Tuesday will bring gusty winds, cooler temperatures and snow showers. The Dweebs do not expect significant accumulations in town at this time. However, the two global models handle the short wave energy differently. The GFS is more consolidated with the upper flow with less splitting then the ECMWF which has a significant split in the flow just before the upper trof moves into the state. Mammoth would be significantly effected by a drier QPF, resulting from the EC’s model handling of the short wave energy. Thus for now…just expect a dusting in town with a few inches over the upper elevations. I will take another look at it over the weekend and comment Sunday. The following system for that following weekend, or the last weekend of the month looks to be a different animal. It will have the support of a strong upper block over AK and a strong upper jet over the North Pacific. Short wave energy is expected to dig a long wave, negative-tilt Trof over the Eastern Pacific and effect all of California with significant precipitation. This may be a protracted period of storminess for our state that following weekend, right on through the end of the month of April. The Climate Forecast Systems outlook based upon the CFS 06Z output from last night shows about 2.5 inches of QPF total for our area of the Sierra through the end of the month. That may be another two feet of snow over the upper elevations!  It also extrapolates in its output, significant precipitation during the month of May, with as much as 1.6 to 1.8 inches of QPF for the Mammoth area. So we may not be quite done yet. Of note…the latest long-range guidance from the 12z Friday the 18th GFS output shows the storm coming in Saturday morning the 26th (Timing Subject to change) has a large cold pool of -10 to -15C at 700MB in the low off shore and at 500MB its cold pool is quite large at -30C.  The upper jet at 300mb is between 130 and 140 Knots. That’s an impressive weather system for the end of April, that could dump a couple of feet over the crest…..should it verify like it is shown.  In that the trof is negative tilt, the upper jet should slide south over the Central Sierra over that weekend, putting Mammoth in that favorable front left exit region. In the meantime, we currently have a mainly convective situation over Mammoth both today and Saturday due to the effects of a small closed upper low moving on shore today over LA.   SE upper flow is indicated over the southern sierra this afternoon and that spells divergence aloft and a good chance of Thunder this afternoon. Infact…the best CAPE with 500  J/KJ are over the Southern Sierra and there is a good conv/divergence 850mb/250mb couplet over Death Valley. Several showers were beginning to crop up on radar over the southern portions of the Southern Sierra about 12:00PM today. The areal coverage should spread a bit north as the day goes on. Thus Mammoth may have a thunder bumper or two today, and this evening and again Saturday as some residual instability is indicated in the models for Saturday.   The weather Sunday and Monday look warmer and then the winds to come up Monday afternoon and into that night with showers possible anytime after midnight Monday and especially Tuesday.   Dr. Howard and the Dweebs………………………:-)